The many references throughout the movie to " Bennie" of course refer to Benzedrine. This amphetamine first registered in 1933 and use for a number of ailments ranging from narcolepsy to obesity and attention deficit disorder,soon grew very popular.It was used or rather abused by servicemen during world war 2, housewives during the 40's and 50's and of course,long haul truck drivers.It was not until 1959 (and maybe as a direct result of this movie),it's use was finally regulated by the US Food and Drug Administration in 1959.I is now a schedule 2 or class B controlled drug used only for certain medical conditions.